Traumatic head injury is a leading cause of death and disability in the teenage population, primarily arising from traffic accidents. The estimated annual cost of treating and rehabilitating victims of head injury is approximately US$2Billion in the United States alone. Most of the neurological damage occurs at the time of injury, though the hours or days following the injury account for addition damage. It is believed that excessive calcium entry into the cells is the biggest threat to brain damage, in which the calcium excess ultimately leads to increased free radicals, proteolysis, initiation of apoptosis, and inflammation. As one of the most important ions in the central nervous system, magnesium is important in various physiological effects, such as ischemia, cellular energy metabolism, and protein synthesis. Magnesium is also a potent calcium channel blocker, and helps to control intracellular calcium activity. Magnesium increases cardiac output and cerebral blood flow. Low levels of magnesium can lead to an increase of intracellular calcium levels. Hypomagnesaemia is a risk to head injuries, and this has been associated with poor neurological outcome and increased mortality. Restoring the levels of magnesium may reduce edema, improve neurological and cognitive outcomes, and help with problems associated with ischemia.